A polymer having a hydrophilic group such as a sulfonic acid group is expected to be applied to various uses. And generally, a method of synthesizing a polymer containing such a sulfonic acid group is limited to a method using a specific vinyl monomer containing a sulfonic acid functional group.
Specific examples of the monomer include sulfonated styrene or AMPS (2-acrylamido-2-methylpropanesulfonic acid).
For example, Japanese Patent Application Laid-Open No. 2002-351147 discloses a copolymer of 2-acrylamido-2-methylpropane sulfonic acid salt as an example of sulfonated styrene and the other vinyl-based monomer which is copolymerizable with it.